In a communication network, it is necessary to always consider the possibility that data communication cannot be performed due to deterioration of signal quality, a failure in a transmission path, or the like. One of countermeasures thereto is a technology of recovery from a failure in which when a failure has occurred, data communication paths are changed, whereby communication is recovered.
In the technology of recovery from a failure, since paths are changed after a failure actually has occurred, there is a possibility that a communication interruption period will be long. Considering in particular the fact that applications requiring a broad band, such as super-high-quality moving image delivery, will appear in the future thanks to increasing network capacity, a large amount of data may be lost even during a very short-time communication interruption, and the influence of a communication interruption on applications can be very large. Accordingly, it is necessary to reduce a communication interruption period as short as possible, preparing for still increasing network capacity in the future.
For this reason, a method is proposed in which before a failure occurs, signal quality over a transmission path is predicted and data communication paths are changed, whereby a communication interruption period is minimized (PTL 1). According to PTL 1, utilizing the phenomenon that quality of radio signals deteriorates depending on the weather state (the amount of rainfall) in a radio network, deterioration of signal quality is predicted based on a forecasted rainfall, whereby paths can be changed before a failure actually occurs due to deterioration of signal quality.
Moreover, PTL 2 discloses a method in which a series of predictions and a historical pattern of past failures are correlated, whereby an occurrence of deterioration of transmission quality is determined in advance and transmission paths are changed.